Damascene processes may be used to “build up” structures for use in a hard drive head, such as a write pole, as opposed to methods which rely upon material removal to form such 3D structures. As applied to formation of PMR writing heads, the damascene process involves forming grooves or trenches in a material, and then depositing (e.g., electroplating) a pole material into the trenches to form write poles. FIG. 1 illustrates a prior art single damascene process. This process involves: 1) providing a trench with targeted angle and track width via, e.g., reactive-ion etching (RIE); 2) depositing multiple layers of thin films including a seed (e.g., ruthenium) layer, to build a narrower trench to control the final pole shape and track width; 3) forming a framed layer 110 by applying a photolithography process (e.g., depositing and photo-developing a photoresist material) to open only the device area for the pole material plating, and then filling the device area through the framed layer with a pole material (e.g., CoNiFe) via a electroplating process; 4) removing the photoresist material by a photo strip; 5) depositing and patterning a chemical-mechanical planarization (CMP) stop layer, e.g., diamond-like-carbon (DLC), followed by deposition of alumina; 6) applying a CMP process to planarize the surface on the diamond-like-carbon; and 7) removing the DLC via, e.g., RIE.
This damascene process scheme may suffer from potential photoresist residue problems. As indicated above, to define the framed layer, the area around the pole is subjected to a photolithography process. Some photoresist residue may remain on the side wall of the poles after the photo developing and stripping. Such photoresist residue can result in poor pole finishing and even device failures. Moreover, it is important to reduce the track width variation of the write poles of the magnetic heads within a wafer and between wafers for high areal density. With the prior art damascene process described above, the standard deviation (1 sigma) of track width may only be controlled to about 10 nm.